Actual Size when blown up to 200 DPI Resolution?

Dear Experts,
Now that I've got my Nikon D70, and taken a few hundred pictures, I
want to make a t shirt from one of the images.
The t shirt people have given me some specs. The image needs
to be 200 DPI or more when it is blown up full size on the t shirt.
I shot everything in L size. The specs for the Nikon D70 are:
Image Size (pixels): 3008 x 2000 [L], 2240 x 1448 [M], 1504 x 1000 [S]
Image Sensor: RGB CCD, 23.7 x 15.6 mm; total pixels: 6.24 million
Effective Pixels: 6.1 million
Who knows how to calculate? Just how big could I blow up
a Large image if I took it to the 200 DPI limit?
15 inches on the long edge?
Here's a bonus question. I also took pictures in 35mm.
If they are scanned at 4000 dpi, how big can I blow them
up to stay within the 200 dpi limit? 20 inches?
Thanks a lot!

Condor_222@yahoo.com

Re: Actual Size when blown up to 200 DPI Resolution?

In article <1158012666.104448.299500@d34g2000cwd.googlegroups.com>,
(stuff deleted)
You may have already figured it out but - 3000 pixels divided by 200 dpi
equals 15 inches. Yes, it is that easy.
Yes, you are right. See, not so hard.

Speers Photography & Design

Re: Actual Size when blown up to 200 DPI Resolution?

That's equivalent to the claim that one halftone line can represent one
whole cycle of a sinusoid. Is that what you meant to say?
David J. Littleboy
Tokyo, Japan

David J. Littleboy

Re: Actual Size when blown up to 200 DPI Resolution?

In article <12ggbv2b93ech40@corp.supernews.com>,
This is standard in the prepress industry. When you print an image using
a certain halftone, the optimal resolution of the image is twice the
halftone frequency. If you print an image with a 150 line halftone, the
image should be 300 pixels per inch for best results. If you print with
a 175-line halftone, the image should be 350 pixels per inch.
The reason is complicated, and applies to things other than just
pictures. It has to do with any sort of data quantization.
Mathematically speaking, if you sample your data at twice the maximum
quantization rate, you'll get the best possible results. Without going
into why it works that way, which is pretty heavy signal processing
theory and beyond the scope of a newsgroup message here, if you are
sampling sound and you want to reproduce tones up to 22kHz, you sample
at 44kHz; if you are quantizing an image, you sample the image at double
the quantization value; and so on.
--
Art, photography, shareware, polyamory, literature, kink:
all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com

Tacit

Re: Actual Size when blown up to 200 DPI Resolution?

In short, the screen (part of the color separation process) is a bunch of
dots or holes that has to be able to distinguish between black, white, or
half-tones. The half tones is the trick - unless the "hole" can pick up
part of the transition between black or white, it will render either black
or white, not the half tone. Color is more complicated, because you are
working in a four color process (CYMK) most of the time, although sometimes
it is printed in three colors - Yellow, magenta and cyan. The color screen
produces tear-shaped dots that are all rotated at an angle from each other.
That's not a great explanation, but reading about color separation,
screening and four color printing is a very interesting and informative
topic. You should look into it, for no other reason than to know the
difference between color pre-press and desktop ink jet printing.
In today's commercial digital ink jet printing, the dpi has to be high
enough to give nearly 100% coverage, based upon the size of the ink
droplets, which vary from one brand/model printer to another.
--
Honest technical and artistic critiques welcomed.
Stan Beck > From New Orleans to Brandon MS
To reply, remove 101 from address.
***

Stan Beck

Re: Actual Size when blown up to 200 DPI Resolution?

The way I take it, they are defining a minimum resolution. Just give
them the way you shoot it, they will do the rest.
Dave Cohen

Dave Cohen

Re: Actual Size when blown up to 200 DPI Resolution?

I'm guessing this applies:
http://en.wikipedia.org/wiki/Nyqvist-Shannon_sampling_theorem
Andrew

Andrew Morton

Re: Actual Size when blown up to 200 DPI Resolution?

Please explain why it is necessary to exceed the resolution
of the screen by that much.

Marvin

Re: Actual Size when blown up to 200 DPI Resolution?

Actually, you always do your comp work at a resolution higher than the final
output, especially when the final output will be printed using separations
and screening - in these cases, you need a dpi resolution at least twice
what the screen will be.
--
Honest technical and artistic critiques welcomed.
Stan Beck > From New Orleans to Brandon MS
To reply, remove 101 from address.
***

Stan Beck

Re: Actual Size when blown up to 200 DPI Resolution?

They can't possibly print on a T-shirt at a resolution that
requires 200 ppi. You can either argue with them, or use an
image editor to increase the number of pixels. At least
they don't ask for 300 ppi, as many printers do when they
aren't printing on paper that can't support that high a
resolution.

Marvin

Re: Actual Size when blown up to 200 DPI Resolution?

Or bother to respond to any of this, esp. as it's x-posted around the
sand lot.In any event, once again DPI is confused with PPI, although
here to no apparent detriment, at least among the many responders.
OP- any 10-4 on any of this?
--
john mcwilliams